Rare Disease Day was last month, but it’s always a good time to raise awareness about unique disorders.

Paroxysmal extreme pain disorder, or PEPD, is a little-known and discussed illness — even among people that are affected by chronic pain. Characterized by skin redness, flushing, and severe pain attacks in various parts of the body, this debilitating condition has been documented by scientific literature and only currently affects 80 individuals, according to a report by the National Library of Medicine. Like many other rare diseases, PEPD is generally thought to be caused by a genetic mutation. This condition often manifests from infancy all throughout a patient’s life, while other studies have pointed to the likely possibility of it being felt even in utero.

Let’s take a closer look at this exceptionally unusual pain disorder and shed further light on PEPD’s history, symptoms, causes, and treatments.

A brief history

PEPD was first described in 1959 by medical researchers who noted their subjects’ severe moments of intense burning pain in the rectum, eye, and jaw. It was only in 1972, when Dr. R.E. Dugan conducted his own research into the disease, that the disease was named—as familial rectal pain syndrome.

This label remained in tact in journals and medical practice for 33 years. Clinicians then resolved to rename it as PEPD in 2005, following patients’ disapproval of the original name and how it ignores the other components of the disease’s symptoms.

“Worse than labor”

As mentioned above, PEPD is characterized by sudden, episodic attacks of burning pain in the rectum, ocular, and mandibular areas of the body. Sometimes, the location of these attacks can relocate as a person suffering from PEPD ages. As most patients experience the disease’s onset in the neonatal period of their lives, it begins to manifest through flushing on one side of the face – often accompanied by a glazed expression and irregular heartbeats. Soon, pain will begin to be felt in lower parts of the body. These attacks are often triggered by bowel movement, which is why many children diagnosed with PEPD also develop constipation in fear of the pain.
Most patients begin with pain in the lower body, and many will move on to experience the same aches in their head and face, most often near their eyes or jaw. Flushing and redness accompany these attacks, which usually correspond with the center of the pain attack. These attacks typically last between a few seconds to several minutes, but more extreme cases have been known to last for hours. Triggers can include sudden changes in temperature, spicy food, cold drinks, and even emotional distress, along with taking medicine and bowel movements. The pain experienced during these attacks is significant: as a study published in the Journal of Neurology explains that patients who have given birth rank PEPD pain as even more severe than labor pain.

In addition to the pain and flushing, non-epileptic seizures and a slow heart rate are also common among PEPD patients.

But what exactly is the cause of these symptoms? Research into the disease have pointed to a mutation in the SCN9A, wherein the voltage-gated sodium channel NaV1.7 experiences an inability to activate. This causes prolonged action potentials and repetitive firing, which then dramatically increases the sensation of pain as well as activity in the sympathetic nervous system. The same gene, when mutated differently, has also been found to cause the opposite phenomenon — the total lack of pain.

Diagnosis, treatment, and management

Like many rare and genetic diseases, diagnosis for PEPD heavily relies on a patient’s medical history, physical exams, and laboratory test results.

Once diagnosed by a healthcare professional, treatment is typically administered through carbamazepine, a drug that has been found to be at least partially effective in lowering the severity and number of pain attacks. Other anti-epileptic drugs, such as gabapentin and topimarate, have only had limited effects.

In terms of managing this disease, as with many rare diseases, close and detailed counseling is crucial in receiving proper treatment. For more information about PEPD, click here.

Reese Jones does freelance data analysis for various health institutions and insurance companies. Her spare time is spent contributing to blogs, tending to her small garden, and caring for her grandmother who has looked after her since she was young.

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